Remember discussing with the Servisair handling agent at Stansted how they checked valid visas for a Finnish airline they handled when the passport was in Russian and the visa was in Finnish, neither of which the local staff at Stansted could speak of course.

They said they were trained to just look somewhere for a date. If there appeared to be a date in the future that was OK. Their computer terminal identified whether visas were required or not when they entered the nationality of the passport.